The latest evolution in MIT's lifelike fish robots (above) has come a long way since Charlie (see the fifth picture).

The new prototype uses just one motor and has six moving parts inside a flexible body, making the robot better able to copy the motion of a real fish, researchers said. And since the body is made of just one piece of soft polymer, there's no chance of water damaging the delicate parts inside.

There won't be any mistaking these for the real thing yet, though. A real fish can swim up to ten body lengths a second. The robot version clocks just one body length a second.